This invention relates to a locking mechanism for a blade of a folding knife or for a similar tool that can be folded and opened either manually or automatically.
Traditionally, the blade of a folding knife or similar tool is locked in an open, extended position by a mechanism included in the knife or other folding tool. One such mechanism includes a circular cylindrical retaining peg, or cross-bolt, urged by a spring into a position in which the cross-bolt prevents the blade from folding, by engagement of a wide diameter portion of the cross-bolt against the surface of a cut-out portion of the base of the blade. By pressing an end of the cross-bolt the user moves it so that the wide diameter portion is disengaged and moves into a recess in the handle, giving the base of the blade clearance to rotate past a smaller-diameter portion of the cross-bolt. Because of the dimensions of the large diameter portion of such a cross-bolt, this mechanism requires a large hole to be cut into the blade to receive the cross-bolt. Such a hole reduces the strength of the blade. Furthermore, such a mechanism is not very robust, since it engages a part of the blade that is located close to the spindle about which the blade rotates between its folded and its opened position.
What is desired, then, is a mechanism for locking a folding blade of a tool such as a knife in an open position without requiring a hole in the blade where it might weaken the blade.
The blade locking mechanism for a folding knife according to the present invention overcomes the aforementioned disadvantage of locking mechanisms utilizing a cylindrical cross-bolt, yet maintains a similar working principle. A first aspect of a locking mechanism according to the present invention is that at least a portion of a locking body is a flat-sided body mounted to be moveable laterally within a handle and urged toward a locking position by a spring included in the handle of the knife or other folding tool, hereinafter referred to for convenience as a folding knife. The locking body has such a shape that when the locking body is moved laterally of the handle to a releasing position, the base of the blade can pass the locking body to move about a blade pivot axis between an open or extended position and a closed or folded position.
In one preferred embodiment of the locking mechanism according to the present invention the locking body is in the form of a modified flat bar slidably fitted in a pair of slots or holes defined in the sides of a handle of the knife, so that a flat surface of the locking body can engage a flat surface on the base of the knife blade when the locking body is moved laterally by a spring included in one of the handles of the knife.
In one preferred embodiment of the invention a laterally-projecting stop member is carried on a portion of the blade and extends from the blade into an opening defined in one of the sides of the handle. The stop is located so as to engage a surface defining the opening in the handle, at positions limiting the range of movement of the blade about its pivot axis, so that the projecting stop member contacting the surface defining the opening, and the locking body contacting a surface of the blade, together prevent the blade from moving in either direction about its pivot axis.
In another embodiment of the invention a surface of a base portion of the blade may be brought to bear against a fixed abutment portion of the handle to prevent movement of the blade about the blade pivot axis in one direction, while the locking body is urged into contact against another surface of the blade and prevents the blade from moving in the opposite direction about the pivot axis.
In one embodiment of the invention a first surface of the locking body bears against one surface of the blade to keep the blade in an opened, extended position, and a different surface of the locking body bears against a different surface of the blade to retain the blade in its closed, folded position with respect to the handle.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.